Check valve for air suspension mechanism

ABSTRACT

A check valve for an air chamber of an air suspension mechanism in which a shock absorber is surrounded by a housing and an elastic body to form the air chamber, includes an air supply tube, a connector welded airtightly to the housing and having on an outer peripheral surface a first thread and on an inner peripheral surface a second thread respectively, a valve body formed of a rubber to converge inward of the housing and having in an inner end a slit, a nut screwed onto the first thread of the connector to fix the valve body to the connector and a mounting nut screwed into the second thread of the connector to removably connect the air supply tube to the connector. The slit of the valve body is expanded by the air supply tube after a thread of the mounting nut is engaged with the second thread of the connector in one or a few screw threads.

This application is a continuation-in-part application of Ser. No.699,123, filed Feb. 7, 1985, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a check valve for an air suspension mechanism,and more particularly to a check valve provided in an air spring of aMacPherson strut type air suspension mechanism for an automobile.

2. Description of the Prior Art

In a MacPherson strut type air suspension mechanism, a shock absorber issurrounded with a housing and an elastic body like a diaphragm to forman air chamber which is filled with compressed air to constitute an airspring.

Now, since in prior art suspensions a connection between the air chamberand a tube for supplying compressed air to the air chamber is notprovided with a check valve for blocking flow of the compressed air fromthe air chamber to the tube, the compressed air in the air chamber leakswhen the tube gets out of place, so that car height might be reduced andadversely effect controllability, riding comfort and may damage thediaphragm.

Also, conventionally, after the suspension is mounted on a car body, theair chamber is connected to an air supply source such as an aircompressor through a tube mounted on the car body to supply compressedair to the air chamber. Thus, since the air chamber can not be filledwith the compressed air until the suspension is mounted on the car bodyto enable the car to be run, air leaking from the air chamber could notbe detected even when the shock absorber, the housing and the diaphragmare manufactured as an assembled unit. Further, since the air chambercould not be filled with dry air before the shock absorber is mounted onthe automobile, a large capacity dryer is needed on the car body.Furthermore, when the suspension is installed in the car body in aproduction line, the car height is reduced to make it difficult toadjust the clearance and alignment of each part in the car body sincethe air chamber is not filled with compressed air.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a checkvalve for an air suspension mechanism which prevents an air chamber fromleaking air when a tube is disconnected.

A further object of the present invention is to provide a check valvefor an air suspension mechanism which can maintain the air chamberfilled with compressed air before a shock absorber is incorporated intoa car body or the automobile is run.

The present invention provides a check valve for an air suspensionmechanism in which a shock absorber is surrounded with a housing and anelastic body to form the air suspension mechanism. The check valvecomprises an air supply tube, a connector having first and second endsthereof separated axially from each other and formed so as to enablesaid air supply tube to be inserted into and removed from said first endthereof, the connector being fixed airtightly to said housing with saidsecond end thereof being disposed inside the housing and the connectorcomprising a threaded portion provided on an interior surface thereofand a mounting nut into which said air supply tube is fitted and havinga threaded portion provided on an exterior surface thereof which is ableto engage with said threaded portion of the connector. The check valvefurther comprises a valve body formed of an elastic material having aslit formed therein and fixed airtightly to said connector, wherein saidslit of said valve body is expanded by said air supply tube after saidthreaded portion of the mounting nut is engaged with said threadedportion of the connector by one or more screw threads and said slit isclosed before said threaded portion of the mounting nut is disengagedwith the threaded portion of the connector.

According to the present invention, when the tube is misaligned thecheck valve serves to prevent the air chamber from leaking air, so thatthe car height is not reduced and so as to maintain controllability andriding comfort and to prevent the elastic body from being damaged.

Since the air chamber can be filled with compressed air, not through atube provided originally in an automobile but through an additionaltube, before or after the suspension mechanism is incorporated into thecar body, the presence of air leakage from the air chamber can beinspected beforehand and clearance and alignment in a production linecan be easily adjusted to reduce the required man-hours for such anoperation.

Since the air chamber can be filled with dry air, the automobile doesnot need to be provided with a large capacity dryer for the suspensionmechanism so that the weight and cost of the automobile can be reduced.

Since the valve body is opened and closed by the tube itself, theconstruction of the suspension mechanism is simple. Also, when the tubeis removed from the connector, pressure in the air chamber acts on thevalve body to press the slit. Consequently, the closing property of theslit itself is improved to increase the effect of preventing airleakage.

The slit of the valve body is formed so as to be expanded by said airsupply tube after the threaded portion of the mounting nut is engagedwith said threaded portion of the connector by one or more screw threadsand to be closed before said threaded portion of the mounting nut isdisengaged with the threaded portion of the connector. As a result, itis easy to connect the supply tube with the connector through themounting nut and safety is ensured, because there is substantially noair escaping from the air chamber through the slit of the valve inconnecting or disconnecting the supply tube.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will become apparentfrom the following description of a preferred embodiment of theinvention with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view showing an essential part of an airsuspension mechanism provided with a check valve according to thepresent invention;

FIG. 2 is a sectional view of the check valve;

FIG. 3 is a right side view of the check valve;

FIG. 4 is a front view of a tube with the upper half being sectioned;

FIG. 5 is a sectional view showing the check valve incorporative thetube; and

FIG. 6 is a right side view of the check valve shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, this invention relates to a check valve 20 for anair suspension mechanism 18 in which a shock absorber 10 is surroundedby a housing 12 and an elastic body 14 to form an air chamber 16.

The shock absorber 10 comprises a cylinder 22 and a piston rod 24connected to a piston slidably arranged in the cylinder 22 andprojecting from the cylinder 22 to the outside. The piston is providedwith a valve through which oil or other liquid received in the cylinderflows when the piston rod 24 is extended and contracted. Saidconstruction is known per se and thus not shown in the drawing. Further,for the shock absorber 10 may be used a so-called monotube type onehaving only a single cylinder in addition to a so-called twin tube typeone provided with the inside and outside cylinders.

The upper end of the piston rod 24 of the shock absorber 10 is connectedto a car body 28 through a support member 26. The support member 26shown in the drawing is provided with first and second bushings 30,32respectively formed of rubber. A collar 34 and the upper cylindrical end13 of the housing 12 are vulcanized and bonded respectively to theinside and outside of the first bushing 30. The upper end of the pistonrod 24 on which a sealing O-ring 35 is mounted extends through thecollar 34, and a nut 36 is screwed onto said end and tightened. Thus,the piston rod 24 is connected to the first bushing 30. On the otherhand, the end 13 of the housing 12 and a fixed plate 38 are vulcanizedand bonded respectively to the inside and outside of the second bushing32. The fixed plate 38 is abutted to the car body 28, and a nut 42 isscrewed onto a bolt 40 extending through the fixed plate 38 and the carbody 28 and tightened to connect the fixed plate 38 to the car body 28.

In the embodiment shown in the drawing, since vibration transmitted fromthe shock absorber 10 to the car body 28 can be received by the firstbushing 30 and vibration transmitted from an air spring to the car body28 by the second bushing 32, the spring constant of the first bushing 30can be set so as to be relatively small and that of the second bushing32 can be set so as to be relatively large. Thus, riding comfort can beimproved. However, the housing 12 may be fixed directly to the pistonrod 24.

The housing 12 comprises the upper cylindrical end 13, a slant portion44 diverging from the end 13, a ceiling portion 45 extending from theslant portion 44 radially outward and an enlarged cylindrical portion 46extending downward from the ceiling portion 45. Into the slant portion44 is fitted a retainer 50 of a bound stopper 48.

The elastic body 14 in the embodiment shown in the drawing is adiaphragm formed cylindrically of rubber. This elastic body 14 is foldedback substantially at the central portion, the outside end beingsandwiched between the enlarged end 46 of the housing 12 and a ring 52and fixed to the housing 12 by caulking the ring 52. The inside end ofthe elastic body 14 is fitted onto an air piston 54 welded to thecylinder 22. Thus, the air chamber 16 is formed in cooperation with thehousing 12 and the elastic body 14.

By providing the air piston 54, the capacity of the air chamber 16 canbe enlarged, and the elastic body 14 can be prevented from directcontact with the outer peripheral surface of the cylinder 22 to reducedegradation of the elastic body 14 due to heat. However, this air piston54 may be omitted. In such a case, the inside end of the elastic body 14is fixed directly to the cylinder 22. The elastic body 14 may be abellows.

The check valve 20 is provided with a connector 60 and a valve body 62as shown in detail in FIGS. 2 and 3.

The connector 60 is formed to removably attach a tube for supplying airand is fixed airtightly to the housing 12. In the embodiment shown inthe drawing, the connector 60 comprises a flange 64, a cylindricalportion 65 extending horizontally from the flange 64, a slant portion 66converging from the cylindrical portion 65, a cylindrical portion 67extending horizontally from the slant portion 66, and abutting portion68 extending radially inward from the cylindrical portion 67 and acylindrical portion 69 extending horizontally from the abutting portion68. The connector 60 is inserted through a hole 61 in the housing 12 andthe flange 64 is welded to the housing 12 over the whole peripherythereof. The cylindrical portion 65 is provided on an interior surfacewith a screw threaded portion 70 and the cylindrical portion 67 isprovided on an exterior surface with a screw threaded portion 71.

The valve body 62 is formed by an elastic material such as rubber andplastic to converge axially of the connector 60 and is provided on anend portion thereof with a slit 73. In the embodiment shown in thedrawing, the valve body 62 as a whole is shaped like a duck billextending from a base 72 having a circular thick portion toward the endwhich has the slit 73. The slit 73 is expanded by the tube when the tubeis connected to the connector as will be later described, and the airchamber 16 communicates to the outside through the slit 73. When thetube is disconnected from the connector, the slit 73 is closed to shutoff communication between the air chamber 16 and the outside.

The base 72 of the valve body 62 is fitted onto the cylindrical portion69 of the connector 60 and a nut 74 is screwed onto the screw thread 71on the exterior surface of the cylindrical portion 67 of the connector60 to urge the base 72 against the abutting portion 68 and to fix thevalve body 62 to the connector 60. Under such a condition the airchamber 16 is shut off from the outside.

In the embodiment shown in the drawing, a tube 80 for supplyingcompressed air is formed of nylon and provided on an end portion with aflange 82 integrally as shown in FIG. 4. Onto the tube 80 are fitted asealing O-ring 84, a spacer 86 and a mounting nut 88 in the mentionedorder. The mounting nut 88 is provided on an exterior surface with athread 89 capable of being screwed onto the thread 70 on the cylindricalportion 65 of the connector 60.

The distance A between an end 81 of the tube 80 and the beginning turn89a of the thread 89 is smaller than the distance B between an abuttingpoint 80a of the tube 80 against the valve body 62 and the beginningturn 70a of the thread 70. The difference of the distances is determinedsuch that the slit 73 of the valve body 62 is expanded by said airsupply tube 80 after the thread 89 of the mounting nut 88 is engagedwith said thread 70 of the connector 60 in one or a few screw threadsand the slit 73 is closed before said thread 89 of the mounting nut 88is disengaged with thread 70 of the connector 60. According to theaforementioned constitution, there is substantially no air escaping fromthe air chamber 16 through the slit 73 in connecting and disconnectingthe tube 80.

The distance C between the end 81 of the tube 80 and an end 83 of theflange 82 is larger than the distance D which corresponds to an axiallength of the cylindrical portion 67 and an axial length of a slantsurface 68a provided in an inner periphery of the abutting portion 68.The difference of the distances is determined such that the O-ring 84contacts an interior surface 67a of the cylindrical portion 67 after theend 81 of the tube 80 is inserted by one or a few milimeters into a boreof the cylindrical portion 69. As a result, O-ring 84 is directedprecisely to a bore of the cylindrical portion 67 without causing anydamage because the O-ring 84 is centered by both threads 70,89 on onehand and by guiding function of the bore of the cylindrical portion 69on the other hand.

The distance E between a shoulder 90 of the mounting nut 88 and the end81 of the tube 80 is determined such that when the mounting nut 88 isfastened to contact closely to the connector 60, the tube 80 abutsagainst the valve body 62 to expand sufficiently the slit 73 in thevalve body 62.

Operation of the embodiment

The tube 80 onto which the mounting nut 88 is fitted rotatably isinserted in the connector 60, and the nut 88 is screwed onto the thread70 of the cylindrical portion 65 of the connector. When the mounting nut88 is so screwed in and the shoulder 90 closely contacts the flange 64of the connector 60 as shown in FIG. 5, it is assured that the mountingnut 88 is sufficiently screwed into said portion 65. Then, the end ofthe tube 80 abuts against the valve body 62 to expand the slit 73 of thevalve body 62 as shown in FIGS. 5 and 6 and the O-ring 84 closelycontacts the inner peripheral surface of the second cylindrical portion67 of the connector 60. Under such a condition, compressed air can besupplied to the air chamber 16 through the tube 80.

When the mounting nut 88 is disconnected from the connector 60 after apredetermined amount of compressed air is supplied to the air chamber16, or when the mounting nut 88 is loosened and the end of the tube 80is separated from the valve body 62, the slit 73 of the valve body 62 isclosed by the elasticity of valve body 62. Under such condition,pressure in the air chamber 16 acts on the valve body 62 to furtherclose the slit 73, so that the airtightness characteristic of the slit73 is sufficiently improved.

Before the suspension mechanism 18 is incorporated in the car body orwhen alignment is adjusted after said suspension mechanism 18 isincorporated and when automobiles are still on the production line, atube other than one to be originally provided on the car body is usedfor the tube 80.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A check valve in an air chamber of an airsuspension mechanism in which a shock absorber is surrounded with ahousing and an elastic body to form said air chamber and a tube isprovided for supplying air to the air chamber, said check valvecomprising:a connector having first and second ends thereof separatedaxially from each other and formed so as to enable said air supply tubeto be inserted into and removed from said first end thereof, theconnector including a threaded portion provided on an interior surfacethereof wherein the housing to which said connector is fixed airtightlywith said second end thereof is disposed inside the housing; a mountingnut into which said air supply tube is fitted and having a threadedportion provided on an exterior surface thereof which is capable ofengaging with said threaded portion of the connector; and a valve bodyformed of an elastic material having a slit formed therein and fixedairtightly to said connector, wherein a distance between an end surfaceof the tube and a beginning turn of said threaded portion of themounting nut is smaller than a distance between an abutting point of thetube against the valve body and a beginning turn of said threadedportion of the connector such that during removal of said mounting nutfrom said connector said slit is closed before said threaded portion ofsaid mounting nut is disengaged from said threaded portion of saidconnector.
 2. A check valve for an air chamber of an air suspensionmechanism as claimed in claim 1, wherein said valve body convergesinward of said housing and said slit is provided in an inner end of saidvalve body.
 3. A check valve for an air chamber of an air suspensionmechanism as claimed in claim 1, wherein said mounting nut includes ashoulder and a distance between said shoulder and the end surface of theair supply tube is of such a length that said slit of the valve body isexpanded by said tube when said shoulder abuts against the connector. 4.A check valve in an air chamber of an air suspension mechanism in whicha shock absorber is surrounded with a housing and an elastic body toform said air chamber and a tube is provided for supplying air to theair chamber, said check valve comprising:a connector having first andsecond ends thereof separated axially from each other and form so as toenable said air supply tube to be inserted into and removed from saidfirst end thereof, the connector including a cylindrical portionextending from an end surface of said second end, an abutting portionextending radially outward from said cylindrical portion and a first anda second threaded portions respectively provided on an exterior and aninterior surfaces of the connector; the housing to which said connectoris fixed airtightly with said second end thereof being disposed insidethe housing; a mounting nut into which said air supply tube is fittedand having a third threaded portion provided on an exterior surfacethereof which is capable of engaging with said second threaded portionof the connector; a valve body formed of an elastic material having aslit formed therein and which is fitted onto an exterior of saidcylindrical portion of the connector; and a nut screwed into said firstthreaded portion of said connector for airtightly fitting said valvebody onto said exterior of said cylindrical portion and wherein an endsurface of said valve body abuts against said abutting portion, whereina distance between an end surface of the tube and a beginning turn ofsaid third thread of the mounting nut is smaller than that between anabutting point of the tube against the valve body and a beginning turnof said second thread of the connector such that during removal of saidmounting nut from said connector said slit is closed before saidthreaded portion of said mounting nut is disengaged from said threadedportion of said connector.
 5. A check valve in an air chamber of an airsuspension mechanism in which a shock absorber is surrounded with ahousing and an elastic body to form said air chamber and a tube having aflange disposed axially from an end surface thereof is provided forsupplying air to the air chamber, said check valve comprising:aconnector having first and second ends thereof separated axially fromeach other and formed so as to enable said air supply tube to beinserted into and removed from said first end thereof, the connectorincluding a first cylindrical portion extending from an end surface ofsaid second end, an abutting portion extending radially outward fromsaid cylindrical portion, a second cylindrical portion extending fromsaid abutting portion and having larger diameter than that of the firstcylindrical portion and a first and a second threaded portionsrespectively provided on an exterior and an interior surfaces of theconnector wherein the housing to which said connector is fixedairtightly with said second end thereof is disposed inside the housing;a mounting nut into which said air supply tube is fitted and having athird threaded portion provided on an exterior surface thereof which iscapable of engaging with said second threaded portion of the connector;a sealing O-ring fitted onto said air supply tube and disposed betweensaid flange of the tube and said mounting nut; a valve body formed of anelastic material having a slit formed therein and which is fitted ontoan exterior of said first cylindrical portion of the connector; and anut screwed into said first threaded portion of said connector forairtightly fitting said valve body onto said exterior of said firstcylindrical portion and wherein an end surface of said valve body abutsagainst said abutting portion, wherein a distance which is substantiallythe length of the second cylindrical portion of the connector is smallerthan that between an end surface of the tube and a surface of theflange, and wherein a distance between an end surface of the tube and abeginning turn of said third thread of the mounting nut is smaller thanthat between an abutting point of the tube against the valve body and abeginning turn of said second thread of the connector such that duringremoval of said mounting nut from said connector said slit is closedbefore said threaded portion of said mounting nut is disengaged fromsaid threaded portion of said connector.